Question
My 2 red oaks in the spring had a lot of buds ready to leaf out.  During this time the lawn care company put Manor and Dimension 2EW as a preemergents.  Also the lawn around the trees was aerorated The leaf buds did not turn to leaves and appear to be drying up.  Some new leaves are developing slowly on the branches but the trees appear to be in distress.  Would the herbicides cause this?

Answer
The pre emergent should not have damaged the roots or the tree. But the aeration IF it was done close to the tree trunk could have damaged the roots. Tree roots are within the first 18-24 inches of the soil. The closer to the trunk the closer to the roots are to the soil surface. IF the work was done close to the trunk than the root could have been damaged. Damaged roots show up as foliage dieback. I think this is what you are seeing. I would try fertilizing the tree with 10-10-10 fertilizer at the rate of 1 lb. per inch of trunk diameter scattered around the tree and watered in good. Apply the fertilizer just before a rain storm and you will not need to water. Also keep the fertilizer away from the trunk about 2 feet. Make sure that you do not use a fertilizer product called Weed and Feed -this contains a herbicide that will kill trees. In fact use only liquid lawn herbicides these are safe to use around trees.